At the main console (hit Backspace), type in:

ALLCAPS                 All weapons, items, ammo
AMMO                    full ammo
ARMOR                   200 % armor
CHOJIN                  become immortal
FREEZE                  (debug) freeze all monsters.
FULLMAP                 view the full map
INVISIBLE               2 minutes of invisibility
KEYS                    all keys
KILL                    kill every thing immediately
REANIMATE               (debug) reanimate all monsters.